A Syrian official "categorically" denied on Monday that the country used chemical weapons during its four-year long civil war.

Deputy Foreign Minister Faisal Mekdad told the Organization for the Prohibition of Chemical Weapons "We wish here to state categorically that we have never used chlorine or any other toxic chemicals during any incidents or any other operations in the Syrian Arab Republic since the beginning of the crisis and up to this very day."

More than 99 percent of the 1,300 tons of chemical weapons Syria declared when it joined OPCW in 2013 have been destroyed. But a European Union envoy slammed Damascus at the annual meeting at The Hague on Monday for what he called "gaps and contradictions" in the country's declarations about its chemical weapons arsenal to the OPCW, which oversees the destruction of toxic armaments.

Jacek Bylica of Luxembourg expressed a lack of confidence that Syrian President Bashar al-Assad's administration had dismantled its entire stockpile.

A deadly chemical attack on the Damascus suburb of Ghouta in 2013 prompted the international push for Syria to join the OPCW. The Syrian government and rebels blamed each other for the attack, which killed hundreds of people.